Summary: The Early Carboniferous to Holocene Browse Basin is a large, offshore hydrocarbon-proven basin on the northwestern Australian poly-phased margin containing more than 15 km of siliciclastic non-marine and marine rocks.

Overview: The Early Carboniferous to Holocene Browse Basin is a large, offshore basin on the northwestern Australian poly-phased margin. The basin is a proven hydrocarbon province, with major undeveloped gas/condensate fields in the outer and central basin, and minor oil discoveries on the basin's eastern margin. The Browse Basin developed during six major tectonic phases: Late Carboniferous to Early Permian extension; Late Permian to Triassic thermal subsidence; Late Triassic to Early Jurassic inversion; Early to Middle Jurassic extension; Late Jurassic to mid-Tertiary thermal subsidence; and Late Miocene inversion. Initial extension resulted in half-graben geometries and the formation of two distinct depocentres, the Caswell and Barcoo sub-basins. These depocentres contain in excess of 15 km sedimentary section, and lie in 100 to 1800 m water depth. The outer Browse Basin comprises the deep-water Scott Plateau (1500 to 5000 m water depth) and Seringapatam Sub-basin. The Carboniferous section is predominantly fluvio-deltaic, and the Permian to Lower Triassic section is mostly marine. Middle to Upper Triassic rocks include fluvial and shallow marine clastics and minor carbonates. Lower to Middle Jurassic syn-rift sediments comprise deltaic and coastal-plain clastics and coal. Widespread erosion occurred in the Callovian, with onlapping Upper Jurassic sandstones and shales providing a thin regional seal across most pre-Callovian structures. Widespread transgression commenced in the Valanginian and peaked in the Turonian, and resulted in the deposition of thick open marine claystones. The Turonian to Cenozoic section records a major progradational clastic-to-carbonate cycle. The Lower Cretaceous claystones provide a thick regional seal and contain potential oil-prone source rocks. Potential source rocks also occur in the Upper Jurassic, Middle to Lower Jurassic, Triassic and syn-rift Palaeozoic sections. Reservoir facies are best developed in sandstones of the fluvio-deltaic Middle to Lower Jurassic section, and in Cretaceous submarine fans of Berriasian, Barremian, Campanian and Maastrichtian age.